To study thetime-effectmodel of PTU thyroid disruption and screen sensitive endpoints.MethodsOvariectomized rats were randomly allocated into 3groups, and propylthiouracil was administered at 5mg/kg BW by gavage for 4,8and 12days respectively. An OVX control and a sham control were also included in the study, treated with corn oil. At the end of the study, serum T₃, T_4and TSH levels, activities of liver type I 5′-deiodinase and malic enzyme were measured correspondingly. Histopathology of thyroid was described and thyroid follicular epithelium/colloid ratio was calculated. ResultsCompared with OVX control, animals treated with PTU showed significantly higher serum T₃, and lower TSH levels, while only 8-day and 12-day groups had significantly lower serum T_4levels. The activity of liver type Ⅰ 5′-deiodinase decreased significantly, while malic enzyme did not show any significant difference among the groups. Histopathology results revealed the hypertrophy of thyroid, disappearance of colloid, adding that the ratio of epithelium versus colloid increased significantly. ConclusionPTU could effectively affect the structure and function of thyroid with time-effect trend; thyroid hormone, type I 5′-deiodinase activity and histopathology endpoints were sensitive; 8-day treatment of thyroid disruptor had the optimal observation.